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Car of the Future

Classroom Activity

Activity Summary
Student teams research and develop a proposal to decrease the carbon footprint of their city's public transportation system through the use of various new technologies and/or alternative fuels. Students prepare a report that explains why their transportation plan is the best one for their community.

Learning Objectives
Students will be able to:

• understand the pros and cons of adopting new technologies or alternative fuels to replace existing gasoline-powered vehicles.

• describe the environmental impact of alternative fuels.

Suggested Time
Four class periods

Multimedia Resources

• NOVA Program Clips QuickTime or Windows Media Video (4 segments, 8-10 minutes each)
• Team 1: Hydrogen Fuel Web Resources
• Team 2: Ethanol Fuel Web Resources
• Team 3: Vehicle Engineering Web Resources
• Team 4: Hybrid and Electric Cars Web Resources

Additional Materials

• Your City's Car of the Future Student Handout (PDF)
• white posterboard
• presentation software (optional)

Background
The United States consumes 25 percent of worldwide oil production, with passenger vehicles accounting for about 40 percent of that. Those same vehicles emit an estimated 400 metric tons of greenhouse gases each year that pollute the air and the environment, and that affect human health. Concerns about air pollution, carbon-dioxide emission, and U.S. dependence on imported oil, along with record-high gasoline prices, are driving research into non-petroleum-based fuels and technology. Currently, some of the most promising alternatives include hydrogen fuel cells, ethanol fuel, and electricity from batteries. In addition, car manufacturers are investigating modifications to existing gasoline-powered cars that can increase energy efficiency and reduce gasoline use.

A hydrogen fuel cell is a device that turns the chemical energy in a fuel directly into electricity. The waste product is water. A single cell consists of a sandwich of two metallic plates with a plastic membrane between them. Hydrogen-rich fuel (derived from gasoline, natural gas, propane, or methanol) is fed to one side of the cell, where it combines with atmospheric oxygen to produce electricity and water. Numerous cells are packed together into a "stack" that can generate enough voltage to power a vehicle or some other electric device. Hydrogen fuel cell vehicles are more efficient than conventional internal combustion engine vehicles and produce no harmful tailpipe exhaust. However, extremely high manufacturing costs, fuel-supply problems, fuel storage problems, limited mileage ability, and cold-temperature sensitivity mean that a mass-market fuel cell vehicle probably won't be available for at least 10–20 years—perhaps much longer.

Ethanol fuel is an alcohol (ethyl alcohol) fuel that can be made from very common renewable materials, such as sugar cane, corn, and cellulose, and is currently the most widely used alternative to gasoline. Ethanol has long been used in motor fuel, usually as an oxygenate additive or blended with gasoline, because ethanol emits less harmful air pollutants than gasoline does. The standard ethanol fuel is called E85, which is a blend of 85 percent ethanol and 15 percent gasoline. However, ethanol contains less energy per gallon than gasoline, so E85-powered vehicles get roughly 30 percent fewer miles per tankful than equivalent gasoline-powered vehicles. In addition, ethanol's lower fuel economy results in more carbon dioxide (CO₂) emissions than a similar gasoline vehicle gives off.

Electricity can be used to power electric and hybrid electric vehicles. Vehicles that run solely on electricity produce no tailpipe emissions. (The only emissions that can be attributed to electricity are those generated in the production process at the power plant.) Electric vehicles operate with electricity that is stored in a battery that must be recharged. They can be plugged into an electricity source wherever there is a suitable outlet. One of the disadvantages of an all-electric vehicle is that it has limited range (about 40–80 miles between charges). Hybrid electric vehicles typically combine the internal combustion engine of a conventional vehicle with the battery and electric motor of an electric vehicle. The combination offers low emissions, with the power, range, and convenient fueling of conventional (gasoline and diesel) vehicles. Unlike electric vehicles, hybrids don't need to be plugged in. Instead, the engine charges the battery while the vehicle is in use.

Energy-efficient technologies include such innovations as new engine technologies, new transmission technologies, and using new materials to create lighter vehicles, all of which increase efficiency and reduce fuel consumption.

Before The Lesson

1. Bookmark the page that includes the four NOVA Program Clips. They focus on new technologies and alternative fuels designed to lessen dependency on fossil fuels. A set of video focus questions is included with each clip.

2. Bookmark the HTML pages with each team's Web resources on class computers (Team 1: Hydrogen Fuel, Team 2: Ethanol Fuel, Team 3: Vehicle Engineering, and Team 4: Hybrid and Electric Cars).

3. Copy enough of the Your City's Car of the Future handout and obtain enough posterboard so that each team will have one handout and one piece of posterboard to work with.

The Lesson

1. Ask students what they think the term "going green" means. What have students or their family members done at home, work, or school to help sustain the planet's natural resources? Brainstorm with students some things they could do to achieve this goal. Ask if any of their family members currently drives an alternative-fuel-powered vehicle. If so, how does it work?

2. Provide each team with the Your City's Car of the Future handout and a piece of posterboard. Tell students they have been hired to help the city go green by decreasing the amount of CO₂ emissions from public transportation in the community. The community's objectives are to:

   1. conserve natural resources
   2. reduce the release of CO₂ into the atmosphere
   3. introduce a new technology or alternative fuel that is reliable, safe, and practical

3. Organize students into four teams to study and work on the objectives and options. Each team will investigate the benefits and drawbacks of a different new technology or an alternative fuel option. After each team has presented its findings, the class will decide as a full committee which option to choose for the city's public transportation system.

4. Assign each student to one of the following teams:

   • Team 1: hydrogen fuel
   • Team 2: ethanol fuel
   • Team 3: vehicle engineering
   • Team 4: hybrid and electric cars

5. Direct students to watch the video clips for their assigned topic. After each team has watched its video clip, have team members answer their team's focus questions, listed with their video clip (find answers in Assessment). Then address any questions students have about their topic and allow them a sufficient amount of time to do their research.

6. Ask teams research their topics using the list of Web sites you provided them, supplemented by any resources they find on their own. Remind students to provide a list of references for the facts they use in their presentations, including the Web sites they use, the name of the person or organization sponsoring the Web site, and (if available) the last time the Web site content was Updated.

7. After student teams are finished preparing their presentation, hold a mock town meeting. If possible, invite another class to view the presentations. They can act as townspeople and can help decide which transportation plan is best for the community. Have students debate the pros and cons of each plan. Encourage them to consider both short-term and long-term solutions, how each plan might be financed, and whether a combination of one or more of the new technologies or alternative fuels might make the most sense for the city.

8. Conclude the activity by voting on which plan (or combination of plans) to adopt based on the evidence presented in the four team proposals.

Video Clip Focus Questions

Team 1: hydrogen fuel

1. What type of emissions do hydrogen fuel cells create? (Water vapor is the only emission.)

2. What are the dangers of using hydrogen as a fuel? (Hydrogen is an extremely volatile element.)

3. What would be the challenge for the United States if it were to convert to hydrogen-fueled vehicles? (Developing an infrastructure for hydrogen fuel.)

Team 2: ethanol fuel

1. Why do critics claim it takes more energy to make ethanol than the amount of energy you get out of it? (While ethanol is a cleaner fuel to burn than gasoline, critics claim that fossil fuels are used not only to produce the fertilizer and pesticides used in cultivating the corn, but also to ferment the corn sugar needed to make the ethanol.)

2. What is cellulosic biomass, and why is it important in the quest to use ethanol as an alternative fuel? (Cellulosic biomass is the woody structure that supports plants. It is important because it could someday be harvested and manufactured without any burning of fossil fuel.)

3. How are bacteria involved in the production of ethanol? (One species of bacteria tears the cellulose apart to release the sugar; another turns the sugar into ethanol.)

Team 3: vehicle engineering

1. How much of the energy stored in gasoline is lost through friction? (Almost half the energy of an engine's combustion chamber is lost to friction as pistons rub against the walls of the cylinder.)

2. Does a car have to be heavy in order to be safe? Explain. (No. Carbon-fiber composite cars can be lightweight while still being strong.)

3. Why would it be difficult for large automakers to produce cars with carbon-fiber bodies? (Carbon fiber is expensive, and molding it into car parts is labor intensive.)

Team 4: hybrid and electric cars

1. How does a hybrid car work? (A hybrid relies on both gasoline and electricity. When the car idles, it uses electricity. At speeds where it is most efficient, the car switches to gasoline. The batteries are being charged while the car is using gasoline.)

2. How can solar energy help fuel hybrid cars? (Energy from the sun can be collected by solar cells and stored in batteries.)

3. Name one drawback of all-electric vehicles. (All-electric vehicles require a lot of batteries to go long distances on a single charge.)

Use the following rubric to assess each team's work.

The "Your City's Car of the Future" activity aligns with the following National Science Education Standards (books.nap.edu/html/nses).

Grades 5-8
Physical Science
• Properties of matter

Science and Technology
• Understandings about science and technology

Classroom Activity Author

Jeff Lockwood taught high school astronomy, physics, and Earth science for 28 years. He has authored numerous curriculum projects and has provided instruction on curriculum development and science teaching methods for more than a decade.